Cranial Cruciate (anterior cruciate) ligament stabilization systems are used on knees that have been traumatized resulting from excess interior rotation or excess cranial movement of the femur in respect to the tibia. An incision is made through lateral aspect of the stifle. The dermis layer is retracted in order to have adequate room to place the lateral suture. The lateral suture is placed, extra-articular, around the lateral fabella and through a hole drilled in the tibial tuberosity or distal patella tendon. The two ends of the suture are than placed through a surgical crimp clamp (primary crimp clamp). Two additional crimp clamps (secondary crimp clamps) are added to the ends that were placed through the primary crimp clamp. Tension is applied, using the secondary clamps as an anchoring point, to the loop. Once the appropriate tension is reached the crimping tool is used to crimp the primary crimp clamp. The secondary crimp clamp are removed and the incision is closed.
The DeAngelis (lateral suture) technique is commonly used in veterinary orthopedic surgery. This technique also places the suture around the lateral fabella and through a hole in the tibial tuberosity. Once the suture is in position the surgeon has to physically pull on the ends of the suture to acquire the desired tension and an assistant must clamp down on the two strands to maintain that tension. After clamping on the suture the surgeon will tie a knot, which will secure the nylon.
The DeAngelis technique does not allow for the accurate adjustment of tension to the stifle joint, it does not maintain the desired loop tension in the suture, and it does not allow larger suture material to be used. This is because the DeAngelis technique requires the surgeon to create the tension, in the suture loop, using physical strength. Therefore it is hard to acquire the adequate/precise tension. Published data shows that 10-15% of the loop tension is lost after the first throw and an additional 10-15% is lost when the dog starts to use the limb (the knot tightens). Also, due to the fact that a knot must be tied there is a limit on the size and strength of the material that can be used due to the suture resistance to bending, the memory of the material and the size of the resulting knot.
The DeAngelis/Lateral suture technique is particularly susceptible to loosening under repeated cyclic loading. The lateral suture technique relies entirely on the knot to preclude loop elongation. A slight amount of loosening due to cyclic loading reduces loop tension in the suture allowing internal rotation and cranial movement of the femur, which would result in lameness of the patient.
The present invention is directed to a tensioning instrument that applies the appropriate tension to the loop and secures the suture so not to allow any loop elongation. The tensioning device includes a first tensioning arm having a proximal end and a distal end, a second tensioning arm having a proximal end and a distal end, a first slot located in the distal end of the first tensioning arm, the first slot allowing for holding of a suture and a second slot located in the distal end of the second tensioning arm, the second slot allowing for holding of a suture. The first tensioning arm is hingedly connected to the second tension arm. The distal end of the first and second arms can form a bend relative to the proximal end of the first and second arms, where the bend allows a user to insert the tensioning device into an incision site.
Preferably, the tensioning device will apply the appropriate tension, maintaining that tension while the surgeon checks the joint for movement. The tensioning device has an angle and slots at the distal tips so that the tips may slide over the suture and apply the tension against the secondary crimp clamps. The angle stops crimp clamp from sliding off the instrument. The crimp clamps are used in place of a knot to secure the suture, significantly reducing loop elongation. The crimp clamp has an oval cross section to allow the desired suture to be place through its center and a specific material properties and wall thickness so that once it is crimped it will stay crimped. Further, a crimping tool is designed so that the exact amount of crimp is applied to the crimp clamp. The dimensions of the crimping area on the crimp tool are such that the crimp tool does not over crimp the suture, which would sever the material, nor does it under crimp the suture, allowing it to slip in the crimp tube. If one tried to crimp a tube using an instrument that was not specifically designed for crimping it would either over crimp the nylon that would cause the nylon to break or it would under crimp the nylon allowing it to slip.
Specifically, the tensioning device has an angle and slots at its distal tips. The slots allow the suture to be placed into the tips of the instrument allowing the secondary crimp clamps to rest against the outer edge of the tip. The angle ensures that the secondary crimp clamp will not slip off the tip during tightening. Preferably, there are ratchets in the handle of the instrument that locks the instrument at a variety of locations, therefore tension can be applied and than checked by the surgeon to ensure adequate tension in the joint. The angled tips of the tensioning device also allow the tool to function as a device to open up the joint to assess the damage and clean out any scare tissue.
The surgical implant crimp clamps have a specific cross section, specific material properties pertaining to the strength of the clamp, and a specific wall thickness that ensures the clamp can be crimped easily enough and hold its deformed state. The cross section is oval shaped allowing the appropriate size suture to be used for the size of animal. The material properties combined with a specific wall thickness ensure that once the clamp is crimped it will maintain the appropriate tension on the suture so that the suture will not slip on break.
The present invention also relates to a crimp tool for use with the crimp having a first arm and a second arm, the first arm having a proximal end and a distal end, the proximal end comprising a handle and the distal end comprising a first jaw and the second arm having a proximal end and a distal end, the proximal end comprising a handle and the distal end comprising a second jaw. The crimp tool also includes a first crimping member integral with the first jaw of the first arm and a second crimping member integral with the second jaw of the second arm. The first arm of the crimp tool is hingedly connected to the first arm;
The crimping tool has oval like areas at each jaw. The dimensions of these oval or radius areas are specific to the crimp clamp being used. The dimensions are such that when the jaws are fully closed the crimp clamp is deformed a specific amount. This ensures that the crimp clamp will not be over crimped, therefore severing the suture and also ensures that the crimp clamp will not be under crimped allowing the suture to slip inside the clamp. The crimping tool is double action, which means there are two pivot points on the tool. This allows the surgeon to crimp the clamp with a fraction of the force that would be necessary if the tool was not double action. This feature of the tool removes the need for appropriate hand strength to fully crimp the clamp.
The present invention also relates to a surgical instrumentation kit having a surgical crimp tube for securing a suture, a tensioning device to adjust the tension of the suture and a crimping tool to crimp the surgical crimp tube over the suture.
The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.